Question

Which of the following structures would be preferable:

# M2M
class UserProfile(models.Model):
    ...
    groups = models.ManyToManyField(Group)

class Group(models.Model):
    ...

or –

# 2 FKs
class UserProfile(models.Model):
    ...

class Group(models.Models):
    ...

class GroupMember(models.Model):
    user = models.ForeignKey(UserProfile)
    group = models.ForeignKey(Group)

Which would be better?

Answer 1

You also can combine these 2 variants using through option

groups = models.ManyToManyField(Group, through='GroupMember')

What do you mean by better? Usually you don’t need to create intermediate model (except the case when you have to store extra data).

ManyToManyField does his job perfectly, so don’t write its functionality by yourself.